Simple Circuits
In collab with JUSTWAY.com
JUSTWAY · CNC Machining
The Right Material
Changes Everything.
A complete guide to every material JUSTWAY offers for CNC machining — metals, plastics, composites — and exactly when to choose each one.
22+
Materials Online
±0.025mm
Tightest Tolerance
3–5
Day Lead Time
150+
Countries Delivered
The Foundation
What is CNC Machining?
Computer Numerical Control (CNC) machining is a subtractive manufacturing process that uses computer-controlled cutting tools to remove material from solid stock — producing parts of exceptional precision and mechanical integrity.
Precision from Solid Stock
Unlike 3D printing which builds up layers, CNC machining starts with a solid block of material and removes everything that isn't the part. This means CNC parts inherit the full mechanical properties of the raw material — no layer lines, no density variations, no voids.
JUSTWAY's platform supports 3-axis and 5-axis CNC milling, CNC turning, and wire-cut EDM, with tolerances as tight as ±0.025 mm following ISO 2768 / GB/T 1804 standards.
Parts can be as small as 2 mm and as large as 2000 mm, with over 30 materials and 10 surface finishes available to order instantly online.
CNC Milling
CNC Turning
Wire EDM
3-axis
5-axis
ISO 2768
Category 01
CNC Machining Metals
From lightweight aerospace alloys to marine-grade stainless steel, JUSTWAY offers 9 metal families for CNC machining, each with specific grade options and surface finishes.
⭐ Most Popular
Aluminum
The go-to material for CNC machining. Exceptional machinability, excellent strength-to-weight ratio, and natural corrosion resistance. Available in multiple alloy grades.
Machinability
Excellent
Weight
Very Light
Corrosion
Good
Cost
Low–Medium
Grades: 6061 (general use, automotive, bicycle frames), 7075 (high-strength, aerospace, automotive frames), 3.3211 (European aerospace spec) · Industries: Aerospace, Automotive, Consumer Electronics, Marine, Food & Pharma · Finishes: Anodize, Bead blast, Brush, Powder coat
Top Pick
Stainless Steel
Renowned for outstanding corrosion resistance and mechanical strength. Available in five grades for everything from kitchen fixtures to surgical instruments and offshore marine hardware.
Machinability
Moderate
Weight
Heavy
Corrosion
Excellent
Cost
Medium
Grades: 304 (versatile, general use), 316/316L (marine, chemical, medical — superior to 304), 303 (free-cutting, high surface finish — bolts, medical), 430, 201 · Note: 316/316L contains molybdenum for enhanced resistance, withstands up to 861°C
Easy to Machine
Brass
An alloy of copper and zinc celebrated for its outstanding machinability, excellent electrical conductivity, and attractive golden appearance. Ideal for precision fittings and valves.
Machinability
Excellent
Conductivity
High
Corrosion
Good
Cost
Medium
Best for: Valves, water pipes, electrical connectors, decorative fittings, precision gears, marine hardware, musical instruments
High Conductivity
Copper
The benchmark for electrical and thermal conductivity. When a component must transfer heat or electricity efficiently, copper is the material of choice — despite being heavier and more expensive than aluminum.
Machinability
Good
Conductivity
Highest
Weight
Heavy
Cost
High
Best for: Electrical connectors, busbars, heat sinks, RF shielding, heat exchangers, electronics components requiring maximum conductivity
Premium
Titanium
The pinnacle of strength-to-weight performance. Titanium alloys are lightweight yet incredibly strong, biocompatible, and resistant to corrosion even in the harshest environments. Requires specialised tooling.
Machinability
Difficult
Strength/Weight
Highest
Corrosion
Excellent
Cost
Very High
Best for: Aerospace frames, medical implants, surgical instruments, high-performance automotive, marine hardware, lightweight structural components
⭐ Popular
Alloy Steel
Carbon steel alloyed with vanadium, silicon, nickel, manganese, copper, or chromium for superior strength and toughness. Includes 40Cr (high-strength mechanical parts, connecting rods, drive shafts) and 45 Steel (gear and shaft-type parts).
Machinability
Moderate
Strength
Very High
Heat Treat
Yes
Cost
Medium
Best for: Connecting rods, drive shafts, gears, structural components, high-strength industrial machinery, fasteners requiring quenching/tempering
⭐ Popular
Mild Steel
The most economical metal for CNC machining. Low carbon content gives good weldability and toughness. Susceptible to surface corrosion without a protective coating, but unbeatable for structural and general-purpose parts.
Machinability
Good
Strength
Medium
Weldability
Excellent
Cost
Low
Best for: Structural frames, brackets, fixtures, enclosures, jigs and tooling, general-purpose industrial parts where corrosion protection will be applied
Hardness Priority
Tool Steel
Engineered specifically for hardness, wear resistance, and the ability to hold a cutting edge at elevated temperatures. The material of choice when making tooling, dies, and punches that must outlast the workpieces they process.
Machinability
Difficult
Hardness
Highest
Wear Resist.
Excellent
Cost
High
Best for: Mould inserts, dies, punches, cutting tools, jigs, gauges, drill bushings, high-wear machine components
High Yield
Spring Steel
Low-alloy manganese or high-carbon steel with an exceptionally high yield strength. Components made from spring steel return to their original shape despite significant deflection or twisting — without permanent distortion.
Yield Strength
Very High
Elasticity
Excellent
Magnetic
Yes
Build Time
3–5 days
Best for: Automotive and industrial suspension, flat springs, clips, retaining rings, snap-fit components, vibration-absorbing parts
Category 02
CNC Machining Plastics
Engineering plastics offer unique combinations of chemical resistance, electrical insulation, low weight, and optical clarity that metals simply can't match. JUSTWAY offers 13 CNC plastic options.
Versatile
ABS
Acrylonitrile Butadiene Styrene. Strong, rigid, impact-resistant, and easy to machine. The standard plastic for consumer electronics, enclosures, and prototypes where dimensional stability matters more than extreme temperature or chemical resistance.
Machinability
Excellent
Impact Resist.
Good
Temp. Limit
~80°C
Cost
Low
Best for: Consumer electronics housings, automotive interior trims, prototype enclosures, signage, appliance components
High Clarity
Polycarbonate (PC)
Combines optical clarity with exceptional impact strength — virtually unbreakable under normal conditions. Widely used when you need transparent or translucent parts that must also survive mechanical loads or elevated temperatures.
Transparency
Excellent
Impact Resist.
Very High
Temp. Limit
~130°C
Cost
Medium
Best for: Safety visors, optical lenses, medical device housings, lighting covers, bulletproof panels, electronic display screens
Wear Resistant
Nylon (PA)
A self-lubricating engineering plastic with excellent wear resistance, chemical resistance, and mechanical strength. Absorbs some moisture which can affect dimensional stability — critical to account for in tight-tolerance designs.
Wear Resist.
Excellent
Self-Lube
Yes
Moisture Abs.
Moderate
Cost
Low–Med
Best for: Bearings, bushings, gears, pulleys, insulators, slide rails, conveyor components, food-contact parts
High Performance
PEEK
Polyether ether ketone — the gold standard of engineering plastics. A semicrystalline thermoplastic with mechanical and chemical resistance properties retained even at high temperatures. Used in applications where metal replacement is the goal.
Temp. Limit
~250°C
Chem. Resist.
Excellent
Biocompat.
Yes
Cost
Very High
Best for: Medical implants, surgical instruments, aerospace structural components, semiconductor equipment, high-temp chemical environments, metal replacement parts
Non-Stick
PTFE (Teflon)
Polytetrafluoroethylene — the lowest coefficient of friction of any solid material. Chemically inert against virtually every substance, biocompatible, and operates from cryogenic temperatures to 260°C. The go-to electrical insulator.
Friction Coeff.
Lowest
Chem. Resist.
Highest
Temp. Range
−200–260°C
Cost
High
Best for: Electrical insulators, chemical seals and gaskets, medical tubing, non-stick surfaces, slide bearings, laboratory equipment
Optical Clarity
PMMA (Acrylic)
Polymethyl methacrylate — crystal-clear optical plastic with 92% light transmittance, better than glass. Stiffer and more scratch-resistant than polycarbonate but less impact-resistant. Polishes to an optically smooth finish.
Clarity
92% Light Trans.
Scratch Resist.
Good
UV Stability
Excellent
Cost
Medium
Best for: Display cases, optical lenses, light guides, signage, aquariums, windows, medical devices requiring visual inspection of fluid
Dimensional Stable
POM (Delrin / Acetal)
Polyoxymethylene — the engineering plastic that most closely mimics metal in CNC machining behaviour. Outstanding dimensional stability, very low moisture absorption, and self-lubricating properties make it ideal for precision moving parts.
Dimensional Stab.
Excellent
Moisture Abs.
Very Low
Self-Lube
Yes
Cost
Medium
Best for: Precision gears, pump impellers, valve bodies, conveyor parts, snap-fits, rollers, food-contact components (FDA compliant)
Extreme Performance
Carbon Fiber
Carbon fiber panels offer the highest strength-to-weight ratio of any machineable material — stronger than steel at a fraction of the weight. CNC machining cuts and drills carbon fiber composite boards to precise final dimensions.
Strength/Weight
Extreme
Weight
Very Light
Stiffness
Highest
Cost
Very High
Best for: Drone frames, motorsport components, aerospace structural panels, prosthetics, premium consumer electronics enclosures, robotics
Quick Reference
Material Comparison
Side-by-side at a glance — machinability, strength, corrosion resistance, and relative cost for every major CNC material on JUSTWAY's platform.
| Material | Category | Machinability | Strength | Corrosion Resist. | Relative Cost | Top Industry |
|---|---|---|---|---|---|---|
| Aluminum 6061/7075 | Metal | Excellent | Medium–High | Good | Low–Med | Aerospace, Auto |
| Stainless 304 | Metal | Moderate | High | Excellent | Medium | Industrial, Medical |
| Stainless 316/316L | Metal | Moderate | High | Superior | Med–High | Marine, Chemical |
| Brass | Metal | Excellent | Medium | Good | Medium | Electrical, Plumbing |
| Copper | Metal | Good | Medium | Good | High | Electronics |
| Titanium | Metal | Difficult | Exceptional | Exceptional | Very High | Aerospace, Medical |
| Alloy Steel (40Cr/45) | Metal | Moderate | Very High | Moderate | Medium | Automotive, Industrial |
| Mild Steel | Metal | Good | Medium | Low | Low | Structural, General |
| Tool Steel | Metal | Difficult | Exceptional | Moderate | High | Tooling, Molds |
| Spring Steel | Metal | Moderate | High | Moderate | Medium | Automotive, Springs |
| ABS | Plastic | Excellent | Medium | Moderate | Low | Consumer Electronics |
| Polycarbonate (PC) | Plastic | Good | High | Good | Medium | Optics, Safety |
| Nylon (PA) | Plastic | Good | Medium | Good | Low–Med | Mechanical Parts |
| PEEK | Plastic | Moderate | High | Exceptional | Very High | Medical, Aerospace |
| PTFE (Teflon) | Plastic | Moderate | Low–Med | Exceptional | High | Chemical, Electrical |
| PMMA (Acrylic) | Plastic | Good | Medium | Good | Medium | Optics, Display |
| POM (Delrin) | Plastic | Excellent | Medium | Good | Medium | Precision Gears |
| Carbon Fiber | Composite | Moderate | Exceptional | Good | Very High | Aerospace, Robotics |
Decision Framework
How to Choose the Right Material
JUSTWAY's engineering team recommends a structured approach to material selection — eight questions that narrow the field from 22+ options to the one that's right for your part.
01
Define Mechanical Requirements
What strength, hardness, and wear resistance does the part need? A decorative panel has different demands to a load-bearing bracket or a rotating gear under constant friction.
02
Map the Operating Environment
Will the part be exposed to extreme heat, moisture, UV, corrosive chemicals, or saltwater? Stainless 316 handles marine environments; PTFE withstands virtually every chemical; PEEK survives 250°C.
03
Check Electrical Requirements
Need conductivity? Choose copper or brass. Need insulation? PTFE is the benchmark. Need a semiconductor housing? Aluminum with anodizing provides both strength and controlled surface conductivity.
04
Weight vs. Strength Trade-off
For weight-critical applications — aerospace, drones, medical implants — titanium or aluminum 7075 give the best strength-to-weight ratios. Carbon fiber panels exceed both for pure stiffness at minimum mass.
05
Assess Machinability
Aluminum and brass are easiest to machine — lower cost, faster lead times. Titanium, tool steel, and PEEK require specialised tooling and longer cycle times, which raises unit cost. Match complexity to budget.
06
Surface Finish Requirements
Metals accept a wide range of post-process finishes: anodize, brush, bead blast, powder coat, black oxide. Plastics may need additional treatment. PMMA can be polished to optical clarity. Factor this in early.
07
Tolerance and Stability
For the tightest tolerances, POM (Delrin) is the best plastic — minimal moisture absorption, exceptional dimensional stability. Among metals, aluminum and stainless hold tight tolerances reliably at scale.
08
Cost and Volume
Mild steel and aluminum minimise unit cost at volume. Titanium and PEEK are reserved for when performance justifies the premium. JUSTWAY's DFM review flags unnecessarily expensive material choices before production.
Post-Processing
Surface Finishes
The material sets the foundation — the finish sets the character. JUSTWAY offers 10 selectable surface finishes, applied directly from the quoting interface so you can see the cost impact before ordering.
As-Milled (Standard)
Ra 125ΞΌin. Fastest turnaround. Visible tool marks with sharp edges and burrs removed. Best when tolerances are critical and cosmetics are secondary.
Anodized
Creates a hard, corrosion-resistant oxide layer. Available in clear, black, red, and gold. Standard for aluminum aerospace and consumer electronics parts.
Bead Blast + Anodize
Bead blasting first creates a uniform matte texture, then anodizing is applied on top. The premium finish for visible aluminum components.
Black Oxide
Conversion coating for stainless steel and mild steel. Improves corrosion resistance and minimises light reflection. Popular for tools and firearm components.
Brushed
Abrasive belts draw directional traces across the metal surface. Primarily aesthetic — the look of premium consumer hardware on aluminium or stainless.
Bead Blast
Removes machining marks and leaves a uniform smooth matte surface. Improves cosmetic appearance and provides a good base for further coatings.
Conductive Oxidation
Film of only 0.01–0.15 ΞΌm — electrically conductive unlike standard anodize. Used when corrosion protection is needed without sacrificing conductivity.
Spray Painting
Available in matt or high gloss. Applied to aluminum, titanium, and plastics with compressed air for uniform, fine droplet coverage. Wide colour range.
Powder Coat (Matt)
Powdered paint baked onto the part in an oven. Creates an extremely durable, chip-resistant surface. Well-suited to structural metal components.
More on Request
If your required finish isn't listed, select 'custom' during quoting. JUSTWAY's engineers will review and source the appropriate treatment for your application.
Live Quoting Tool
Material, grade, color, and finish — configured in one screen
JUSTWAY's instant quoting interface — select material, alloy grade, color, and one of 10 surface finishes, with any spec discrepancies flagged before you order.
Applications
Industry Applications
Material choice is inseparable from industry. Here's how JUSTWAY's material library maps to the sectors that rely on precision CNC machining.
Aerospace
Aluminum 7075, Titanium, PEEK, Carbon Fiber — all chosen for extreme strength-to-weight ratios and temperature resistance.
Automotive
Aluminum 6061, Stainless 304, Alloy Steel (40Cr) — balance of machinability, strength, and cost at production volume.
Medical
Stainless 316/316L, Titanium, PEEK, PTFE — biocompatible, sterilisable, FDA/EU MDR-compliant materials for implants and instruments.
Robotics
Aluminum, POM, Nylon, Carbon Fiber — lightweight rigid structures combined with self-lubricating plastic bearings and gears.
Electronics
Copper, Brass, Aluminum (anodized), PC, PTFE — conductivity for signal paths, insulation for housings, thermal management.
Marine
Stainless 316/316L, Aluminum, Brass — chosen specifically for resistance to saltwater corrosion and mechanical loads in wet environments.
Industrial
Mild Steel, Alloy Steel, Tool Steel, Nylon — from structural frames and fixtures to precision gears and high-wear tooling components.
Start with the Right Material.
Get an Instant Quote.
Upload your CAD file to JUSTWAY — select from 22+ materials, configure your finish, and get a quote within 2–4 hours. Parts delivered in as little as 3 days worldwide.
Get an Instant CNC Quote →22+
Materials Online
±0.025mm
Tolerance
3 days
Fastest Lead Time
150+
Countries
Simple Circuits
This article is produced in collaboration with JUSTWAY. All specifications, material properties, tolerances, and capabilities are based on publicly available information from JUSTWAY.com and verified technical sources. Affiliate links may be present.
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